The efficient and fast coating of boards with a poured material is becoming increasingly important, especially with regard to the one-sided or two-sided coating of printed circuit boards, for example with solder resist. For that purpose, for example, the widely known curtain pouring process is used, the basic mode of operation of which is described in EP-A-0 002 040 and also in numerous other protective rights. The curtain pouring process essentially operates by transporting a board to be coated (e.g. the aforementioned printed circuit board) beneath a pouring head. The pouring head is arranged transversely to the transport direction of the board being coated. The poured material (e.g. the solder resist) descends from the pouring head in the form of a pouring curtain and falls onto the board located below the pouring head, while the board is being transported, essentially along a line running transversely to the transport direction. The continuous transportation of the board through and beneath the pouring curtain results in the whole board's being coated with poured material.
That process works perfectly well and it, as well as several variants thereof, is used in the printed circuit board-manufacturing industry for the coating of printed circuit boards. Because there is a clear prevailing trend towards ever smaller finished articles and also, as a result, towards ever fewer and smaller printed circuit boards in each finished article, circuit boards that are printed on both sides are now already used in very large numbers and, in many cases, are even the standard. Such circuit boards that are printed on both sides often also have so-called through-platings.
When such printed circuit boards are being coated, the pouring curtain and, as a result, the poured material naturally falls also onto the regions of the board where such through-platings are provided. Consequently, on the other side of the board and in the through-platings themselves there are formed so-called "blobs of coating", which have to be removed by means of correspondingly lengthy and, as a result, troublesome washing-out. Furthermore, it has emerged that, when the board is coated using the conventional curtain pouring process, the distribution of the poured material along the line of impact of the pouring curtain on the board and, as a result, over the width of the whole board is not always sufficiently homogeneous.